Japanese Laid-Open Patent Publication No. 7-310632 describes a remote engine starter system. When a vehicle is parked in a state in which its doors are locked and the engine is stopped, the engine can be started from a remote location with the remote engine starter system by operating an electronic key. The system includes a remote receiver, which is arranged in the vehicle to receive radio waves on the UHF band. When the electronic key is operated, the electronic key transmits an engine start request signal on UHF radio waves. The remote receiver receives the engine start request signal and authenticates the signal to verify the electronic key. When the electronic key is verified, the system starts the engine.